Extended state observer based load frequency controller for three area interconnected power system

In this paper, we develop a new extended state variable observer based LFC scheme for three-area interconnected power systems. The extended state observerbased load frequency controllers are developed which utilize disturbance estimation techniques. The propose control approach assures that the fluctuating things of the load frequencies reaches to a safer range and the load frequencies can also be made at a very minimal not to have an effect on power quality and power flow in multi-area interconnected power system. The results of the simulations using MATLAB/SIMULINK done did not only address that the proposed newly control method works effectively but also change powerfully the parameter variations of the interconnected areas of the power system. Especially, it works very well to limit disturbances impact on interconnected areas in the system. Therefore, the performance of interconnected power system under different multi-conditions is simulated with the new control method to demonstrate the feasibility of the system

A fed-batch fermentation process for poly (3-hydroxybutyrate-co-3-hydroxyvalerate) production by Yangia sp. ND199 using molasses as substrate

A locally isolated halophilic bacterium, Yangia sp. ND199 was able to use molasses as substrate for copolymers poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] production. Cell dry weight (CDW) of 6.37 g/l, P(3HB-co-3HV) content of 43.1 wt% and P(3HB-co-3HV) concentration of 2.75 g/l were obtained by Yangia sp. after 60 h of cultivation in flask. In a batch cultivation mode in a fermentor, the CDW was increased to 9.1 g/l but P(3HB-co-3HV) content was decreased to 37 wt%. Fed-batch fermentation with two different nutrient feeding strategies was used. High CDW of 54.8 g/l was obtained after 54 h of cultivation but P(3HB-co-3HV) content was still low (39.8 wt%). Two-step fed-batch fermentation with two different nutrient feeding strategies was then designed. High CDW of 50 g/l and P(3HB-co-3HV) content of 52.9 wt% were obtained after 54 h of cultivation. The two-step fed-batch process designed here for the production of P(3HB-co-3HV) by Yangia sp. ND199 can be developed and used for further studies

Optimal linear quadratic Gaussian control based frequency regulation with communication delays in power system

In this paper, load frequency regulator based on linear quadratic Gaussian (LQG) is designed for the MAPS with communication delays. The communication delay is considered to denote the small time delay in a local control area of a wide-area power system. The system is modeled in the state space with inclusion of the delay state matrix parameters. Since some state variables are difficult to measure in a real modern multi-area power system, Kalman filter is used to estimate the unmeasured variables. In addition, the controller with the optimal feedback gain reduces the frequency spikes to zero and keeps the system stable. Lyapunov function based on the LMI technique is used to re-assure the asymptotically stability and the convergence of the estimator error. The designed LQG is simulated in a two area connected power network with considerable time delay. The result from the simulations indicates that the controller performed with expectation in terms of damping the frequency fluctuations and area control errors. It also solved the limitation of other controllers which need to measure all the system state variables

THE VIEWS OF SOME ECONOMIC THEORIES ON THE ECONOMIC CRISIS OF CAPITALISM AND SOME LESSONS FOR VIETNAM

After a brief analysis of the views presented in the economic theories of neo-liberalism, Keynes and Marx on the economic crisis of capitalism the authors of this article point out some methodological recommendations for the development of socialistic-oriented market economy in Vietnam. The experience of dealing with the crisis shows the importance of upholding the advantages of socialist regime: the leadership of the Communist Party in appropriate policyguidelines, the role of the Government in its consistent implementation of its policies, the role of the state's economic sector in sustaining the stability of the whole economy as well as in economic recovery, the contribution and support by the people for the common cause of development of Vietnam

Disturbance observer-based controller for inverted pendulum with uncertainties: Linear matrix inequality approach

A new approach based on linear matrix inequality (LMI) technique for stabilizing the inverted pendulum is developed in this article. The unknown states are estimated as well as the system is stabilized simultaneously by employing the observer-based controller. In addition, the impacts of the uncertainties are taken into consideration in this paper. Unlike the previous studies, the uncertainties in this study are unnecessary to satisfy the bounded constraints. These uncertainties will be converted into the unknown input disturbances, and then a disturbance observer-based controller will be synthesized to estimate the information of the unknown states, eliminate completely the effects of the uncertainties, and stabilize inverted pendulum system. With the support of lyapunov methodology, the conditions for constructing the observer and controller under the framework of linear matrix inequalities (LMIs) are derived in main theorems. Finally, the simulations for system with and without uncertainties are exhibited to show the merit and effectiveness of the proposed methods

Applying Conflict Management Styles to Resolve Task Conflict and Enhance Team Innovation

Task conflicts among group members have a significant impact on team creativity, so it is critical to identify which conflict resolution styles should be used. This paper aims to examine how various conflict management styles influence team creativity via task conflict. The empirical research was conducted using the Structural Equation Model (SEM) for a sample of 257 employees working for Vietnamese organizations. The results show that dominating style increases task conflict while combining and obliging styles reduce it. To take advantage of the creativity-related benefits associated with task conflict, team leaders should develop an open atmosphere that encourages participants' integrating styles, rather than dominating styles. The negative influence of obliging style reflects Vietnamese culture's high collectivism. The study provides various approaches for task conflict management and also highlights the role of controlling task conflicts in enhancing team innovation. It implies that employees will be able to work better as a team in practice if conflict management strategies are used in a flexible manner. It helps them to build a good connection and successfully implement new ideas. Further research should extend the conclusion of this analysis in various contexts to generalize the findings. Doi: 10.28991/esj-2021-01303 Full Text: PD

RECOVERY OF POLY(3-HYDROXYBUTYRATE) FROM Yangia sp. ND199 BY SIMPLE DIGESTION WITH SODIUM HYPOCHLORITE

Polyhydroxyalkanoate (PHA) is a biodegradable polymer synthesized intracellularly by many microorganisms. After extraction from the cells, they possess the common features of non-toxic, biocompatible, biodegradable and recyclable. These features render them highly competitive with polypropylene or other petroleum-derived plastics, especially in medicine. The isolation and purification of PHA from bacterial cells are the key step of PHA production process. There are several methods have been used for OHA purification, these include solvent extraction, enzymatic hydrolysis, and chemical digestion. In this study we used chemical digestion method for purification of PHB from Yangia sp. ND199. Among various chemical tested (NaOH, HCl, KOH, NaOCl, and SDS), NaOCl was found as an efficient chemical for PHB recovery and PHB purity from Yangia sp. ND199. The optimal purity and recovery conditions were a ratio of 1:1 (v/v, solution containing 100 g/l bacterial cells and solution containing 6% NaOCl), a 30 oC temperature and a 1 h treatment time. Under such conditions, a purity of 99% and a recovery of 94% were obtained. This method is sumple and can be developed and used for industrial scale

Measuring and Evading Turkmenistan's Internet Censorship: A Case Study in Large-Scale Measurements of a Low-Penetration Country

Since 2006, Turkmenistan has been listed as one of the few Internet enemies by Reporters without Borders due to its extensively censored Internet and strictly regulated information control policies. Existing reports of filtering in Turkmenistan rely on a small number of vantage points or test a small number of websites. Yet, the country's poor Internet adoption rates and small population can make more comprehensive measurement challenging. With a population of only six million people and an Internet penetration rate of only 38%, it is challenging to either recruit in-country volunteers or obtain vantage points to conduct remote network measurements at scale. We present the largest measurement study to date of Turkmenistan's Web censorship. To do so, we developed TMC, which tests the blocking status of millions of domains across the three foundational protocols of the Web (DNS, HTTP, and HTTPS). Importantly, TMC does not require access to vantage points in the country. We apply TMC to 15.5M domains, our results reveal that Turkmenistan censors more than 122K domains, using different blocklists for each protocol. We also reverse-engineer these censored domains, identifying 6K over-blocking rules causing incidental filtering of more than 5.4M domains. Finally, we use Geneva, an open-source censorship evasion tool, to discover five new censorship evasion strategies that can defeat Turkmenistan's censorship at both transport and application layers. We will publicly release both the data collected by TMC and the code for censorship evasion.Comment: To appear in Proceedings of The 2023 ACM Web Conference (WWW 2023

Somatic embryogenesis and plant regeneration from leaf callus with genetic stability validation using SCoT markers in Paramignya trimera, a medicinal plant native to Vietnam

Xao tam phan (Paramignya trimera (Oliv.) Guillaum) is a medicinal plant native to Vietnam, that is renowned for its therapeutic properties, particularly for the treatment of various ailments, including cancer. This study investigated in vitro propagation of P. trimera through somatic embryogenesis and shoot organogenesis using leaf callus. Various culture media, plant growth regulators, malt extract, and carbon sources were evaluated to optimize callus induction and somatic embryo formation from leaf explants. DNA barcoding confirmed 96.96% to 100% homology with P. trimera specimens from Khanh Hoa province, Vietnam. The highest callus formation rate, reaching 100%, was observed in one-year-old explants cultured in Woody Plant Medium (WPM) supplemented with 2.0 mg L-1 naphthaleneacetic acid (NAA) and 0.2 mg L-1 benzylaminopurine (BAP) in the dark for over six weeks. In WPM supplemented with 30 g L-1 sucrose, 4.0 mg L-1 BAP, and 500 mg L-1 malt extract, globular stage embryos developed into embryoids and shoots and buds clumped at 10 and 18 weeks, respectively. Shoot organogenesis was observed in WPM supplemented with 30 g L-1 sucrose and 0.07 mg L-1 thidiazuron (TDZ) after 18 weeks of culture. Genetic fidelity assessments using 12 SCoT markers indicated that in vitro plantlets were homologous to the mother plant. This study provides a viable method for the conservation and sustainable cultivation of Xao tam phan, ensuring a stable supply of this valuable medicinal resource

Incidence of dengue and chikungunya viruses in mosquitoes and human patients in border provinces of Vietnam

Background: Dengue virus remains a major threat in Vietnam, while chikungunya virus is expected to become one. Surveillance was conducted from 2012 to 2014 in Vietnam to assess the presence of dengue and chikungunya viruses in patients hospitalized with acute fever in five Vietnam provinces neighboring Lao PDR and Cambodia. Surveillance was extended to mosquitoes present in the vicinity of the patients' households. Results: A total 558 human serum samples were collected along with 1104 adult mosquitoes and 12,041 larvae from 2250 households. Dengue virus was found in 17 (3%) human serum samples and in 9 (0.8%) adult mosquitoes. Chikungunya virus was detected in 2 adult mosquitoes (0.18%) while no chikungunya virus was detected in humans. Differing densities of mosquito populations were found, with the highest in the Long An Province border with Cambodia. Long An Province also displayed the lowest rate of infection, despite a very high Breteau Index, high human population density and presence of the main cross border road system. The highest incidence was found in Dac Nong Province, where the Breteau and Container indices were the second lowest. Dengue virus was detected in five Aedes albopictus, three Aedes aegypti and one Culex vishnui. Chikungunya virus was detected in two Ae. aegypti. All infected mosquitoes belonged to haplotypes described in other parts of the world and a number of novel haplotypes were found among uninfected mosquitoes. Conclusions: Dengue is considered to be regularly introduced to Vietnam from Cambodia, mostly through human movement. The data reported here provides a complementary picture. Due to intensive international trade, long-distance transportation of mosquito populations may play a role in the regular importation of dengue in Vietnam through Ho Chi Minh City. It is important to decipher the movement of mosquitoes in Vietnam, not only at the Lao PDR and Cambodia borders but also through international trade routes. Mosquito surveillance programs should address and follow mosquito populations instead of mosquito species